:ES 
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XVII. 

Descriptions  of  New  Species  of  Fossils,  from  the  Cretaceous  Formations  of  Nebraska, 
with  Observations  upon  BACULITES  OVATUS  and  B.  COMPRESSUS,  and  the  Progressive 
Development  of  the  Septa  in  Baculites,  Ammonites,  and  Scaphites.  , 

BY  JAMES/ HALL  AND  F.  B.  MEEK. 


j 


(Communicated  June  27,  1854.) 


THE  collections  which  have  furnished  the  following  new  species  from  the  cretaceous 
formation  of  the  Upper  Missouri,  were  made  in  the  summer  of  1853,  by  Mr.  F.  B. 
Meek  and  F.  V.  Hayden.  The  collection  of  Mammalian  remains  from  the  Tertiary 
period  has  been  placed  at  the  disposal  of  Professor  Leidy,  for  his  forthcoming  new 
memoir  upon  the  fossil  remains  of  that  region. 

CALLIANASSA  DANAI,  n.  sp.     (Fragment.) 
PLATE  I.  FIG.  1,  a,  I. 

Exterior  surface  convex,  inner  surface  flat,  upper  and  lower  edges  obtusely  angular ; 
fingers  nearly  as  long  as  the  hand ;  upper  one  nearly  triangular  in  section  and  de- 
pressed above  near  its  articulation,  and  marked  along  its  upper  edge  at  regular  intervals 
by  four  small  foramina,  outer  side  depressed  above  the  middle  and  towards  the  lower 
margin,  and  marked  by  two  large  foramina,  dividing  the  whole  into  three  nearly  equal 
spaces ;  upper  angle  obtuse,  lower  edge  sharp  and  smooth,  arcuate  from  the  apex  back 
a  little  more  than  half  the  distance  to  the  base,  from  which  point  it  curves  again 
towards  the  articulating  extremity,  leaving  the  widest  part  near  the  middle.  Lower 
finger  narrower  than  the  upper,  equal  in  length,  bending  slightly  downwards  from 
the  hand,  and  thence  gradually  curving  upwards  to  the  extremity,  marked  on  the 
upper  slope  of  the  outer  angle  by  two  foramina,  one  near  the  base  and  one  near  the 


MG24943 


380  DESCRIPTIONS    OF    NEW    SPECIES    OF    FOSSILS, 

centre.  Section  sub-triangular,  centre  of  the  outer  side  forming  an,  obtuse  angle,  the 
lower  edge  more  acute,  the  inner  side  flat,  and  the  upper  edge  acute,  and  finely  den- 
ticulated near  the  hand,  gradually  becoming  less  prominent  and  finally  obsolete 
on  the  outer  half  of  the  edge.  Surface  smooth  and  polished,  showing  no  external 
marks,  but,  through  the  translucent  shell,  a  kind  of  reticulation,  owing  to  inequalities 
beneath. 

Locality  and  Position.  —  Great  Bend  of  the  Missouri.  Lower  part  of  division  No.  4 
of  Section. 

LlNGULA    SUBSPATULATA,    n.  Sp. 
PLATE  I.  Fia.  2,  a,  I. 

Shell  sub-elliptical,  margins  regularly  curved  above,  straight  or  little  contracted 
below  the  centre  ;  base  sub-truncate ;  surface  marked  by  faint  concentric  striae,  and  a 
few  strong  wrinkles  parellel  with  the  lateral  margins.  Viseral  impression  trifoliate. 

The  only  specimen  we  have  is  imperfect,  and  the  shell  is  preserved  only  on  the 
margins.  It  has  nearly  the  proportions  of  Lingula  RovUniana,  (D'Orbigny,  Pal. 
Frangaise,  Terrains  Cretaces,  Brach.  p.  10,  pi.  490,  fig.  1,)  but  differs  in  having  its 
greatest  width  above  the  middle,  while  in  the  European  species  the  greatest  width  is 
below  the  middle.  Our  species  is  also  more  abruptly  rounded  or  sub-truncate  at  the 
base.  The  surface  markings  are  similar. 

Locality  and  Position.  —  Near  Red  Cedar  Island,  thirty-five  miles  below  Fort  Pierre. 
Division  No.  4  of  Section. 

CAPRINELLA  CORALOIDEA,   n.  sp. 
PLATE  II.  FIG.  3,  a-f. 

Our  specimen  is  a  portion  of  the  larger  valve  extending  about  two  and  a  half  inches 
from  the  apex,  and  partially  invested  with  the  thick,  fibrous  shell.  From  this  is  drawn 
the  following  description. 

Inferior  valve  spiral,  rapidly  increasing  from  the  apex  towards  the  aperture  ;  when 
divested  of  the  outer  fibrous  shell,  the  internal  septate  part  is  seen  to  be  spirally 
curved,  and  rapidly  increasing  in  size ;  a  longitudinal  groove  or  depression  extends 
from  the  apex  along  the  back  of  the  curve  to  the  larger  extremity,  crossed  by  numer- 
ous irregular  septa,  which  pass  from  the  inner  side  outwards  and  upwards. 

This  interior  septate  portion  is  enveloped  in  a  thick,  fibrous  shell,  which,  in  the 


FROM  THE  CRETACEOUS  FORMATION  OF  NEBRASKA.  381 

l 

imperfect  specimen,  is  much  thicker  on  the  inner  than  on  the  outer  side  of  the 
volution ;  fibres  longitudinal,  consisting  of  four  or  six  angled,  more  or  less  flattened 
prisms,  which  are  crossed  at  regular  intervals  of  less  than  their  diameter  by  septa  or 
diaphragms,  and  externally  marked  by  fine  transverse  striae,  the  whole  presenting  an 
appearance  like  a  small  columnar  Favosite  or  Chaetetes. 

This  specimen  differs  from  the  species  figured  by  D'Orbigny,  in  being  curved  not 
exactly  in  the  same  plane,  in  increasing  much  more  rapidly  in  size  from  the  apex, 
and  in  having  the  fibrous  portion  of  the  shell  so  thick  upon  the  inner  side  of  the 
volution  as  to  bring  the  sides  in  contact  if  continued  a  single  turn.  The  septa  are 
also  much  more  irregular  than  in  the  European  species,  those  which  are  distinct  upon 
the  back  of  the  shell  often  converging  so  that  two  unite  in  a  single  one  on  the  inner 
side  of  the  volution. 

The  differences  noticed  suggest  an  inquiry  whether  the  generic  description  of 
Caprinella  should  be  modified ;  since  it  seems  impossible  that  a  shell  of  this  character, 
from  its  extreme  thickness  on  the  inner  side,  and  from  its  rapidly  increasing  size,  could 
have  formed  several  volutions.  An  examination  of  more  perfect  specimens  will  proba- 
bly show  the  necessity  of  such  modification,  or  the  establishment  of  a  new  genus. 

Locality  and  Position.  —  Sage  Creek,  Nebraska.  Upper  part  of  division  No.  4  of 
Section. 

PECTEN  RIGIDA,  n.  sp. 
PLATE  II.    FIG.  4,  a,  i,  c. 

Shell  obovate,  height  greater  than  length,  very  gradually  narrowing  towards  the 
hinge ;  valves  equally  convex ;  hinge  line  short ;  wings  minute,  nearly  equal,  anterior 
one  truncate,  posterior  one  pointed,  striated  upon  the  surface;  left  or  inferior  valve 
marked  by  strong,  concentric  undulations ;  superior  valve  smooth,  or  marked  in  the 
exfoliated  shell  by  faint  radiating  striae.  Length,  .19  inch ;  height,  .23  inch. 

The  strong  concentric  undulations  of  the  inferior  valve  are  likewise  conspicuous  on 
the  cast,  and  are  there  crossed  by  radiating  striae.  The  superior  valve,  which  has  the 
shell  partially  exfoliated,  shows  only  faint  radiating  striae  without  concentric  undula- 
tions as  in  the  other  valve.  Perfect  specimens  may  perhaps  show  other  markings  on 
the  superior  valve  not  visible  in  these. 

Locality  and  Position.  —  Sage  Creek,  Nebraska.  Upper  part  of  division  No.  4  of 
Cretaceous  Strata. 


382  DESCRIPTIONS    OF    NEW    SPECIES    OF    FOSSILS, 

AVICULA  HAYDENI,  n.  sp. 
PLATE  I.  FIG.  5,  a,  b. 

Shell  small,  sub-rhomboidal,  oblique ;  beak  small,  pointed,  slightly  elevated  above  the 
hinge  line ;  hinge  line  straight,  less  than  the  length  of  the  shell,  and  pointed  at  the 
posterior  extremity,  anterior  extremity  short,  rounded;  posterior  margin  obliquely 
truncate ;  no  line  of  demarcation  between  the  wing  and  body  of  the  shell ;  basal 
margin  forming  a  regular  elliptic  curve ;  surface  marked  by  sharp  strong  ribs,  with 
sometimes  an  intermediate  smaller  one,  crossed  by  faint  concentric  undulations  and 
parallel  fine  lines  of  growth.  Length,  .3  inch ;  height,  .22  inch  ;  hinge  line  making 
an  angle  with  the  posterior  slope  of  about  129°. 

All  the  specimens  we  have  seen  are  of  the  left  valve  only.  The  shell  is  extremely 
thin  and  fragile,  and  preserved  only  upon  portions  of  one  of  our  specimens.  Some 
individuals  show  a  depressed  line  along  the  hinge  margin. 

Locality  and  Position.  —  On  the  Missouri,  near  Red  Cedar  Island,  twenty-five  miles 
below  Fort  Pierre.  From  division  No.  4  of  Section. 

LUCINA    SUBUNDATA. 
PLATE  I.  FIG.  6,  a,  b. 

Shell  sub-orbicular ;  length  a  little  greater  than  height ;  beak  little  elevated,  sub- 
central  or  nearer  the  posterior  side ;  anterior  margin  broadly  rounded,  posterior  one 
sloping  from  the  beak  and  rounded  below ;  surface  with  concentric  undulations  and 
finer  parallel  lines,  crossed  by  very  minute  radiating  strise.  Length,  A  inch  ; 
height,  .36  inch ;  width,  .2  inch. 

This  shell  bears  some  general  resemblance  to  L.  cornuelana  of  D'Orbigny,  (  Terrains 
Cretaces,  p.  116,  pi.  281,  fig.  3,)  but  the  beaks  are  much  less  elevated,  the  anterior  end 
much  broader,  and  the  concentric  undulations  larger  and  less  uniform.  This  species 
strikingly  possesses  the  characters  of  the  genus  Lucina,  and  may  readily  be  distin- 
guished among  the  smaller  bivalves  from  this  region. 

Locality  and  Position.  —  Sage  Creek.    Upper  part  of  division  No.  4  of  Section. 

CYTHEREA  ORBICULATA,  n.  sp. 

PLATE  I.    FIG.  7. 
Shell  thick,  sub-orbicular ;  beak  moderately  elevated  and   near  the  anterior  side ; 


FROM  THE  CRETACEOUS  FORMATION  OF  NEBRASKA.  383 

posterior  margin  regularly  rounded  ;  surface  marked  by  fine  equal  concentric  lines. 
Length,  .18  inch;  height,  1  inch;  width,  .66  inch. 

The  form  is  neatly  rounded  throughout,  the  umbones  curving  gently  towards  the 
antero-cardinal  margin.  Our  specimens  of  this  shell  are  all  imperfect. 

Locality  and  Position.  —  On  the  Missouri,  five  miles  below  James  River.  Calcareous 
beds  of  the  base  of  division  No.  2  of  Section. 

CYTHEREA  TENUIS,  n.  sp. 
PLATE  I.    FIG.  8,  a,  J,  c. 

Shell  thin,  ovate-orbicular,  length  and  height  nearly  equal ;  beak  elevated,  nearly 
central ;  anterior  and  posterior  extremities  rounded,  the  latter  somewhat  broader ; 
surface  marked  by  concentric  undulations  and  fine  parallel  striae.  Length,  .4  inch ; 
height,  .36  inch. 

This  is  a  fragile  shell  with  beaks  more  nearly  central  than  the  preceding  species. 
It  is  much  more  delicate  than  any  shell  of  this  family  which  has  been  found  in  the 
cretaceous  formation  of  this  region. 

Both  this  and  the  preceding  species  are  referred  to  the  genus  Cytherea  from  external 
form,  no  opportunity  having  offered  of  examining  the  hinge. 

Locality  and  Position.  —  Same  as  preceding. 

CRASSATELLA  EVANSII,  n.  sp. 
PLATE  I.   FIG.  9,  a-e. 

Shell  obliquely  ovoid  (varying  somewhat  in  form),  ventricose  ;  beaks  much  elevated ; 
anterior  margin  short,  rounded  below;  postero-cardinal  margin  sloping  abruptly  down- 
wards, the  extremity  sub-truncate ;  basal  margin  distinctly  and  neatly  crenulated  on 
the  interior ;  escutcheon  broad  lanceolate,  well  defined ;  lunule  distinct,  but  margins 
not  strongly  defined ;  surface  somewhat  undulated,  marked  by  fine  irregular  striae  or 
lines  of  growth  ;  muscular  impressions  strongly  marked. 

This  shell  is  probably  identical  with  the  imperfect  cast  figured  by  Dr.  D.  D.  Owen 
in  his  Report,  PI.  7,  fig.  9,  as  a  Pectunculus.  Our  specimens  showing  the  interior  of 
the  hinge,  muscular  impressions,  etc.,  are  from  the  same  position  in  the  series,  and 
from  the  same  district  of  country.  The  shell  is  a  well-marked  Crassatella,  presenting 
all  the  ordinary  characteristics  of  the  genus,  in  the  cardinal  and  muscular  characters.  It 
is  abundant,  occurring  entire  and  in  the  condition  of  casts.  The  species  may  be  readily 


384  DESCRIPTIONS    OF    NEW    SPECIES    OF    FOSSILS, 

distinguished  by  its  oblique  form  and  extended  beaks,  its  ventricose  character,  and  the 
fibrous  or  striated  structure  of  the  interior,  produced  by  exfoliation.  It  occurs  more 
commonly  in  the  septaria,  which  furnish  only  casts,  the  shell  adhering  to  the  rock  on 
breaking,  while  the  entire  specimens  are  only  obtained  from  the  clay.  Length,  1.4 
inches  ;  height,  .97  inch ;  width,  .70  inch. 

Locality  and  Position.  —  Sage  Creek,  in  the  upper  part  of  division  No.  2  of  Section. 

PECTUNCULUS  SIOUXENSIS,  n.  sp. 
PLATE  I.  FIG.  12. 

Shell  sub-orbicular  (in  the  cast) ;  beaks  elevated,  nearly  central ;  longer  than  high, 
nearly  convex ;  anterior  margin  regularly  rounded ;  posterior  margin  somewhat 
obliquely  sub-truncated ;  basal  margin  without  crenulations ;  cardinal  margin  curved 
and  marked  by  fine  dividing  crenulations ;  posterior  muscular  impression  strong. 

The  specimen  described  is  a  cast  preserving  the  form  of  the  shell,  and  showing  very 
distinctly  the  crenulations  of  the  cardinal  margin.  The  external  markings  of  the 
shell  are  unknown. 

Locality  and  Position.  —  Mouth  of  Big  Sioux,  on  the  Missouri  River,  in  a  fer- 
ruginous sandstone.  Division  No.  1  of  Section. 

NUCULA   SUBNASUTA,    n.  Sp. 
PLATE  I.  FIG.  10,  a,  J,  c. 

Shell  sub-elliptical,  contracted  towards  the  posterior  extremity,  somewhat  ventricose 
in  the  middle ;  a  shallow  groove  or  depression  extending  obliquely  from  the  beak  to 
the  base  of  the  shell,  where  it  produces  a  slight  indentation  in  the  regular  elliptic 
curve  of  the  basal  margin ;  escutcheon  margined  by  a  broad  shallow  groove,  extending 
from  near  the  beak,  and  causing  a  faint  emargination  near  the  posterior  extremity 
above ;  beaks  nearly  central,  small  and  incurved ;  shell  marked  by  faint  striee  or  lines 
of  growth,  and  a  few  broader  concentric  undulations  which  give  a  scarcely  perceptible 
inequality  to  the  surface;  crenulations  of  the  hinge  line  very  fine.  Length,  .78  inch  ; 
height,  .45  inch;  width,  .36  inch. 

This  neat  little  shell  is  sufficiently  well  marked  to  be  readily  distinguished,  particu- 
larly by  the  slight  impression  on  the  edges  of  the  shell  above  and  below  near  the 
posterior  extremity.  The  crenulations  are  fine  and  slender ;  and  in  one  specimen  the 
erosion  of  the  shell  exhibits  the  crenulated  edge  of  a  former  hinge  line,  at  some  dis- 


FROM    THE  CRETACEOUS    FORMATION    OF    NEBRASKA.  385 

tance  from  the  present  one ;  showing  that  the  shell  increased  by  additions  to  its  car- 
dinal, as  well  as  ventral  margin. 

Locality  and  Position.  —  Sage  Creek.     Upper  part  of  division  No.  4  of  Section. 

NUCULA    VENTRICOSA,    H.  Sp. 
PLATE  I.   FIG.  11,  a,  b. 

Shell  ventricose  in  the  middle  and  depressed  at  each  end,  ovate,  prolonged  posteriorly, 
somewhat  regularly  rounded  in  front,  contracted  behind ;  a  broad  shallow  impression 
extending  from  below  the  beak  to  the  postero-ventral  margin  of  the  shell ;  beaks  ele- 
vated, nearer  to  the  anterior  extremity ;  basal  margin  regularly  rounded  to  near  the 
posterior  end ;  surface  marked  by  regular,  distinct  concentric  ridges,  which  are  strong 
upon  the  middle  of  the  shell,  and  become  somewhat  abruptly  obsolete  as  they  pass  to 
the  depressed  parts  at  either  extremity;  hinge  line  slightly  curved;  crenulations 
strong.  Length,  .14  inch  ;  height,  .09  inch  ;  width  about  the  same  as  height. 

This  minute  shell  is  distinguished  by  its  ventricose  middle  and  depressed  extremities, 
and  by  the  strong  concentric  ridges  becoming  almost  abruptly  obsolete  in  passing  from 
the  ventricose  portion  of  the  shell  to  the  flatter  extremities ;  the  teeth  of  the  hinge  line 
are  comparatively  strong.  The  mature  character  of  the  shell  is  indicated  by  its  thick- 
ness, as  well  as  by  the  strong  concentric  ridges ;  while  several  casts  of  the  same  dimen- 
sions were  found  associated  with  it. 

Locality  and  Position.  —  Sage  Creek.     In  division  No.  4  of  Section. 

CAPULUS  OCCIDENTALIS,  n.  sp. 

PLATE  I.    FIG.  13,  a- d. 
Orbicula  (undet),  OWEN,  Report.  PI.  vn.  Fig.  II. 

Sub -orbicular,  patelliform ;  base  nearly  flat ;  very  depressed,  conical  above  ;  the  apex 
intermediate  between  the  centre  and  margin ;  lower  surface  marked  by  fine  lamellose 
imbricating  radiations,  which  diverge  from  a  point  nearly  opposite  the  apex  of  the 
convex  side,  and  are  crossed  by  concentric  undulations.  The  convex  side  is  distinctly 
marked  by  a  horseshoe-form  muscular  impression,  which  is  connected  at  its  two 
extremities  by  a  fainter  parallel  impression  ;  muscular  impression  marked  transversely 
by  radiating  striae,  which  are  continued  obscurely  beyond  it  to  the  margin,  and  which, 
in  the  muscular  impression,  are  crossed  by  finer  concentric  lines. 

VOL.    V.    NEW    SERIES.  52 


386 

Small  fragments  of  pearly  nacreous  shell  adhere  to  a  few  points  on  the  flatter  side, 
but  they  present  no  markings  of  any  kind. 

We  have  identified  this  fossil  as  the  Hipponix  (Defranc),  Pileopsis  capulus,  de- 
scribed under  the  genus  Cabochon  by  Des  Hayes.  Our  specimen  is  the  smaller  valve, 
very  distinctly  marked  on  its  upper  surface  by  the  muscular  impression  which  may 
be  the  cast  of  the  interior  of  the  other  valve,  and  on  the  lower  surface  by  imbricating 
striae,  very  much  like  those  of  the  Hipponix  (Pileopsis)  patelloidea  (Des  Hayes,  Coc. 
Foss.,  Tom.  II.  PL  III.  figs.  23,  24,  and  25).  It  may  also  be  compared  with  other 
species  of  this  genus  as  figured  by  Des  Hayes. 

Locality  and  Position.  —  Sage  Creek,  Nebraska,  from  division  No.  4  of  the  Section 
of  the  cretaceous  formation. 

INOCERAMUS  SUBL^EVIS,  n.  sp. 
PLATE  II.  FIG.  1,  a,  J. 

Shell  comparatively  thin,  moderately  convex,  length  about  one  fifth  more  than 
height ;  hinge  line  long  and  straight,  forming  an  angle  of  about  130°  with  the  front ; 
anterior  extremity  rounded  ;  posterior  side  long  and  rounded  at  the  extremity ;  beaks 
small,  scarcely  elevated  above  the  hinge  line ;  surface  with  nearly  obsolete  concentric 
undulations,  and  fine  regular  concentric  striae,  which  continue  almost  as  distinct  where 
the  shell  is  partly  exfoliated. 

The  most  striking  feature  of  this  shell  is  the  almost  entire  absence  of  concentric 
undulations,  by  which  it  will  at  once  be  distinguished  from  any  species  heretofore 
described  from  that  region,  or  even  in  this  country.  It  differs  from  the  I.  sagensis 
of  Owen  in  the  lesser  obliquity  of  the  shell,  in  the  more  extended  and  rounded  anterior 
extremity,  and  in  the  smaller  and  less  elevated  beaks,  while  the  entire  shell  is  less 
convex.  The  fine  equal  concentric  striae,  and  faint  radiating  lines  with  obsolete  undu- 
lations, are  usually  sufficient  to  distinguish  this  shell,  even  where  the  surface  is  much 
exfoliated.  Our  specimens  do  not  show  the  whole  outline,  but  it  can  be  inferred  by 
the  direction  of  the  concentric  striae. 

Locality  and  Position.  —  Great  Bend  of  the  Missouri,  in  division  No.  4  of  Section. 

INOCERAMUS  CONVEXUS,  n.  sp. 
PLATE  II.   FIG.  2,  a,  J. 

Shell  ovate,  very  convex,  height  a  little  more  than  three  fourths  of  length ;  beaks 
prominent ;  hinge  line  long  and  straight,  forming  an  angle  with  the  anterior  margin  of 


FROM  THE  CRETACEOUS  FORMATION  OF  NEBRASKA.  387 

about  145° ;  anterior  side  somewhat  extended  and  regularly  rounded ;  posterior  side 
extended  (and  probably  subtruncated).  Shell  marked  by  strong  undulations,  which 
are  simple  at  their  extremities,  while  some  of  them  become  divided  towards  the  centre 
of  the  shell,  where  they  are  prominent,  being  less  conspicuous  towards  the  beak,  and 
almost  obsolete  towards  the  base  of  the  shell.  Concentric  lines  mark  the  surfaces  of 
exfoliated  specimens  somewhat  irregularly. 

This  species  differs  from  the  I.  sagensis  in  the  less  obliquity  of  the  form,  and  the 
greater  extension  of  the  anterior  side  of  the  shell,  giving  an  angle  with  the  hinge  line 
of  50°  greater  than  in  that  species.  The  concentric  undulations  in  I.  sagensis  are 
more  simple  than  in  this  species,  and  more  persistent  towards  the  base  of  the  shell, 
while  this  is  more  ventricose  in  the  middle.  This  shell  appears  to  differ  sufficiently 
from  all  described  species  known  to  us,  to  render  it  easily  recognizable. 

Locality  and  Position.  —  Sage  Creek.     Upper  part  of  division  No.  4  of  Section. 

INOCERAMUS  TENUILINEATUS,  n.  sp. 
PLATE  II.   FIG.  3,  a,  I. 

Shell  obliquely  rhomboid-ovate,  height  a  little  more  than  two  thirds  the  length ; 
beaks  towards  the  anterior  extremity,  elevated,  ventricose,  and  incurved;  hinge  line 
straight,  making  an  angle  with  the  anterior  margin  of  about  100°;  posterior  side  ex- 
tremely elongated  and  rounded  at  the  extremity;  surface  marked  by  irregular  undula- 
tions, which  are  nearly  obsolete  on  exfoliated  specimens.  A  small  portion  of  the  external 
surface  remaining  near  the  anterior  extremity,  shows  minute  crowded  concentric  striae. 

This  shell  has  the  form  and  obliquity  of  I.  sagensis,  but  the  beaks  are  more  elevated 
and  incurved,  and  the  umbonial  region  more  ventricose,  while  the  undulations  are  much 
less  conspicuous,  irregular,  and  more  obtuse.  The  portion  of  the  external  surface 
observed  has  the  strise  much  finer  and  more  closely  crowded  than  in  /.  sagensis.  This 
species  resembles  in  form  the  J.  impressus  of  D'Orbigny,  (Terrains  Cretaces,  p.  515,  pi. 
409,)  except  in  the  extension  of  the  hinge  line,  which  we  have  not  been  able  to  see  in 
its  perfect  condition. 

Locality  and  Position.  —  Sage  Creek  and  Great  Bend  of  the  Missouri.  Division  No. 
4  of  Section. 

INOCERAMUS  CONRADI,  n.  sp. 

PLATE  II.   FIG.  5,  a,  I. 
Shell  very  thin,  ventricose ;  surface  marked  by  numerous  fine  concentric  stria3  or 


388  DESCRIPTIONS    OF   NEW    SPECIES    OF    FOSSILS, 

lines  of  growth,  apparently  destitute  of  undulations,  structure  fibrous,  fibres  coarse 
and  angular. 

The  only  specimen  we  have  of  this  fossil  has  an  appearance  as  if  the  two  valves  had 
been  crushed  in  the  direction  of  the  length  of  the  shell,  presenting  a  view  of  the  ante- 
rior end.  We  refer  this  specimen  to  the  genus  Inoceramus,  for  the  reason  that  the 
shell  is  fibrous  in  its  texture,  being  thicker  towards  the  margin  and  thinner  towards 
the  beaks,  precisely  similar  in  these  respects  to  the  external  fibrous  portions  of  the 
shells  of  this  genus. 

In  its  surface  markings  this  shell  differs  from  any  cretaceous  species  hitherto  de- 
scribed, so  far  as  known  to  us,  either  in  this  country  or  in  Europe ;  and  more  resembles 
the  Liasic  and  Oolitic  species  as  figured  by  Goldfuss ;  and  in  its  surface  marking  it  may 
be  compared  with  I.  laevigatus^  (Munster)  Goldfuss,  Petrefacta,  II.,  p.  Ill,  ta.  109, 
fig.  6.  This  species  is  associated  with  I.  fragilis  and  Ammonites  percarinatus. 

Locality  and  Position.  —  On  the  Missouri  River,  five  miles  below  the  mouth  of 
Vermilion  River.  Lower  part  of  division  No.  2  of  Section. 

INOCERAMUS  FRAGILIS,  n.  sp. 
PLATE  II.   FIG.  6,  a,  I. 

Shell  small,  thin,  obliquely  rhomboid-obovate,  height  a  little  less  than  length ;  beaks 
acute,  pointed  forward ;  hinge  line  straight,  or  slightly  concave,  extended  somewhat 
less  than  the  length  of  the  shell ;  forming  a  nearly  right  angle  with  the  anterior  side ; 
marked  by  comparatively  strong  undulations,  which  expand  upon  the  body  of  the 
shell,  and  become  less  prominent  towards  the  base ;  surface  of  the  shell  marked  by  finer 
concentric  lines. 

The  shell  of  this  species  is  extremely  fragile,  and  appears  to  be  fibrous  throughout  its 
entire  thickness.  In  general  appearance  it  resembles  the  Inoceramus  mytiloides  of  Man- 
tell,  as  figured  by  Roemer,  but  the  hinge  line  is  more  extended,  and  forms  a  more  obtuse 
angle  with  the  anterior  side,  and  the  height  is  proportionally  greater.  It  differs  ex- 
tremely from  the  /.  mytiloides  as  given  by  Goldfuss ;  and  it  also  differs  widely  from 
D'Orbigny's  figures  of  I.  problematicus,  which  Roemer  regards  as  identical  with 
I.  mytiloides  of  Mantell. 

Locality  and  Position.  —  On  the  Missouri  River,  five  miles  below  the  mouth  of 
Vermilion  River.  In  the  lower  clay  beds  of  division  No.  2  of  Section ;  associated 
with  a  small  species  of  Ammonites,  etc 


FROM  THE  CRETACEOUS  FORMATION  OF  NEBRASKA.  389 

NATICA  OBLIQUATA,  n.  sp. 
PLATE  III.  FIG.  1,  a,  b. 

Shell  longer  than  wide,  very  obliquely  sub-ovate,  spire  little  elevated.  Volutions 
three  to  three  and  a  half,  convex ;  last  one  ventricose,  prolonged  in  front.  Suture 
deeply  impressed.  Surface  marked  by  faint,  very  fine,  closely  arranged  lines  of  growth, 
which  are  crossed  by  fine,  nearly  obsolete,  revolving  lines.  Aperture  ovate,  somewhat 
oblique.  Umbilicus  small,  and  partly  closed  by  the  deflected  pillar  lip.  Columella 
marked  with  a  distinct  opercular  impression,  which  continues  down  to  the  base  of  the 
aperture.  Spiral  angle  92°.  Length,  .36  inch;  breadth,  .32  inch.  Body  volution,  .7 
of  whole  length. 

Locality  and  Position.  —  Great  Bend  of  the  Missouri.  From  the  clay  beds  of  division 
No.  4  of  Section. 

NATICA  CONCINNA,  n.  sp. 
PLATE  III.  FIG.  2,  a  -  d. 

Shell  obliquely  sub-ovate ;  length  and  breadth  nearly  equal.  Spire  little  elevated. 
Volutions  three  and  a  half,  convex ;  last  one  ventricose.  Suture  sharply  impressed. 
Surface  nearly  smooth,  or  marked  only  with  exceedingly  fine,  closely  arranged  lines  of 
growth,  which  are  invisible  to  the  naked  eye.  Aperture  ovate,  obtuse  at  both  extrem- 
ities. Umbilicus  of  medium  size,  round.  Columellar  lip  not  thickened,  slightly  de- 
flected upon  the  body  volution,  but  not  so  as  to  cover  any  part  of  the  umbilicus. 
Spiral  angle  92°.  Length,  .22  inch ;  breadth,  .23  inch.  Body  volution  .75  of  the 
whole  length. 

In  form  this  shell  bears  much  resemblance  to  the  N.  obliquata.  The  difference  in 
size,  however,  can  hardly  be  due  to  age,  as  this  appears  to  be  a  mature  shell. 

Locality  and  Position.  —  Sage  Creek.  Higher  part  of  the  upper  clay  formation,  No. 
4  of  Section. 

NATICA  PALUDIN^FORMIS,  n.  sp. 
PLATE  III.  FIG.  3,  a,  Z>,  c. 

Shell  sub-rhomboidal,  obliquely  conical  above,  prolonged  below ;  spire  extremely 
elevated ;  volutions  five  to  five  and  a  half,  convex ;  suture  deeply  impressed  or  sub- 
canaliculate  ;  surface  ornamented  with  numerous  fine,  closely  arranged  lines  of  growth, 


390  DESCRIPTIONS    OF    NEW    SPECIES    OF    FOSSILS, 

which  are  crossed  by  fine,  slightly  undulating,  sub-equal,  revolving  lines,  presenting 
under  the  magnifier  a  beautiful  cancellated  appearance.  Aperture  oval,  approaching 
sub-ovate,  narrower  above,  oblique;  outer  lip  thin ;  pillar  lip  not  thickened ;  umbilicus 
obsolete  or  none.  Spiral  angle  57°.  Length  (of  largest  specimen),  .9  inch  ;  breadth, 
.6  inch.  Last  volution,  .6  of  whole  length. 

This  shell  resembles  very  closely  the  N.  cassisiana  of  D'Orbigny,  (Terrains  Cretaces, 
p.  166,  pi.  175,  figs.  1-4,)  but  differs  in  its  more  acutely  elevated  spire.  The  surface 
markings  are  also  quite  different,  the  lines  of  growth  being  regular  and  distinct,  while 
the  revolving  lines  are  not  punctate,  as  in  D'Orbigny's  species ;  and  the  aperture  of 
tlie  latter  is  proportionally  wider  below.  In  general  form  this  species  approaches 
the  N.  Clementina  and  N.  Icevigata  among  the  Cretaceous  species,  and  several  Oolitic 
species  figured  by  D'Orbigny,  Pal.  Frangaise,  Terrains  Jwrassiques. 

Locality  and  Position.  —  Great  Bend  of  the  Missouri  River  and  Sage  Creek,  division 
No.  4  of  the  Section. 

ACTEON    CONCINNUS,    n.  Sp. 
PLATE  III.  FIG.  4,  a-d. 

Shell  globose  or  sub-oval ;  spire  very  short ;  volutions  three  and  a  half  to  four ; 
suture  narrow,  but  distinct ;  surface  brilliant,  with  a  porcelain-like  polish,  and  orna- 
mented with  about  thirty  equidistant  punctate  revolving  grooves  or  strise.  Aperture 
narrow,  semilunar,  contracted  at  the  posterior  extremity,  rounded  in  front.  Columella 
with  one  strong  fold  at  the  base,  and  a  broad,  deep  spiral  depression  above  it.  Spiral 
angle  about  100°.  Length,  .17  inch;  breadth,  .15  inch.  The  last  volution  .88  of 
whole  length. 

Locality  and  Position,  —  This  beautiful  little  species  is  found  at  Sage  Creek,  in  con- 
nection with  Baculites  ovatus,  B.  compressus  (Say),  Scaphites  nodosus  (Owen),  £c. 
Also  at  Great  Bend  of  the  Missouri.  In  the  upper  and  lower  parts  of  No.  4  of 
Section. 

BUCCINUM?  VINCULUM,  n.  sp. 

PLATE  III.  FIG.  5,  a,  I. 

Shell  below  the  medium  size,  elongate-ovate ;  spire  moderately  elevated ;  volutions 
about  five  or  six,  convex,  regularly  rounded ;  suture  strongly  impressed ;  surface 
marked  by  numerous  strong  longitudinal  folds,  and  at  irregular  intervals  with  strong 
varices ;  fine  lines  of  growth  parallel  to  those  ridges  cover  the  entire  surface ;  these 


FROM  THE  CRETACEOUS  FORMATION  OF  NEBRASKA.  391 

are  crossed  by  rounded,  elevated  revolving  bands,  separated  by  spaces  less  than  twice 
their  width.  Aperture  unknown ;  canal  —  ?  Spiral  angle  about  4°  50' ;  length  of 
imperfect  shell,  .6  inch.  Last  volution  more  than  half  the  whole  length;  breadth,  .35 
inch. 

This  shell  has  the  general  aspect  of  Buccinum,  though  its  superficial  characters 
leave  some  doubts,  which,  from  the  imperfection  of  the  base  of  the  shell,  cannot  be 
entirely  removed  by  the  most  careful  examination  of  our  specimen.  The  surface  has 
been  marked  by  several  strong  varices,  which  in  this  specimen  are  all  exfoliated,  leav- 
ing a  groove,  with  several  pits  or  indentations  formed  by  the  denticulations  of  the  lip. 
The  elevated  revolving  bands  constitute  a  distinguishing  feature  of  the  shell,  having  a 
uniform  character,  and  appearing  like  strips  of  enamel  laid  over  the  surface. 

Locality  and  Position.  —  Great  Bend.     Lower  part  of  division  No.  4  of  Section. 

Fusus  SHUMARDII,  n.  sp. 
PLATE  III.  FIG.  6,  a,  J,  c. 

Shell  elongate  fusiform ;  spire  elevated  ;  volutions  six  or  more,  moderately  convex ; 
suture  defined,  not  deeply  impressed ;  surface  marked  by  strong  longitudinal  obtuse 
folds,  which  are  equal  to  the  spaces  between  them,  and  by  finer  lines  of  growth, 
crossed  by  strong  elevated  revolving  bands  wider  than  the  spaces  between  them,  with 
sometimes  an  intermediate  smaller  one.  Aperture  slightly  oblique,  narrow,  obtusely 
angular  behind,  and  gradually  narrowing  in  front  into  the  prolonged  canal;  canal 
slightly  bent  and  twisted.  Spiral  angle  about  35°.  Length,  .66  inch ;  width,  .25  inch. 
The  last  volution  .55  of  the  whole  length. 

The  almost  equal  proportions  between  the  spire  and  length  of  aperture,  and  the 
elongated  form  of  the  shell,  are  conspicuous  features.  The  longitudinal  folds  are 
slightly  curved  on  the  volutions  of  the  spire ;  the  revolving  bands  are  flat,  and  under 
a  magnifier  show  well  defined,  angular  edges. 

Locality  and  Position.  —  Great  Bend  of  the  Missouri.  Lower  part  of  division  No. 
4  of  Section. 

\ 
Fusus  CONSTRICTUS,  n.  sp. 

PLATE  III.  FIG.  7,  a  -  d. 

Shell  fusiform ;  spire  moderately  elevated  (imperfect  above  in  our  specimen) ;  volu- 
tions five  or  six,  convex;  suture  distinct;  surface  marked  by  strong  longitudinal 


392  DESCBIPTIONS    OF    NEW    SPECIES    OF    FOSSILS, 

rounded  folds,  which  are  about  equal  to  the  spaces  between  them  ;  crossed  by  revolving 
bands,  wider  than  the  spaces  between  them,  and  distinctly  defined  upon  the  longitudinal 
folds  and  in  the  spaces.  Aperture  narrow,  oblique,  obtusely  angular  behind,  gradually 
contracting  in  front  into  a  narrow  canal ;  outer  lip  thick ;  columella  broad ;  a  distinct 
spiral  groove  or  constriction  marking  the  junction  of  the  canal  with  the  inflated  part  of 
the  last  volution.  Spiral  angle,  52°.  Breadth,  .1  inch. 

This  shell  presents  all  the  external  characters  of  Fusus,  but  the  imperfection  of  the 
columella  renders  it  impossible  to  determine  fully  its  character.  The  impressed  or 
constricted  line  at  the  base  of  the  last  volution  passes  around,  parallel  with  the 
revolving  lines,  into  the  aperture,  and  may  have  produced  a  fold  upon  the  inner  lip, 
which  might  be  a  sufficient  reason  for  removing  it  from  this  genus.  The  suture  is  a 
narrow  constricted  line,  impressed  nearly  at  right  angles  to  the  direction  of  the  spire, 
and  the  depressions  between  the  longitudinal  folds  are  terminated  abruptly  above, 
before  reaching  the  suture,  by  an  irregular  ridge  caused  by  the  extension  and  thicken- 
ing of  the  upper  extremities  of  the  folds. 

Locality  and  Position.  —  Sage  Creek.     Upper  part  of  division  No.  4  of  Section. 

FUSUS  1    TENUILINEATA,    U.  Sp. 
PLATE  III.  FIG.  8,  a-  c,  and  fig.  9,  a  -  c. 

Shell  elongate-terete ;  volutions  (number  unknown)  slightly  convex  in  the  middle, 
last  one  flattened,  or  sometimes  slightly  concave  above  the  middle;  aperture  sub- 
rhombic,  terminating  in  an  acute  angle  behind,  and  narrowing  in  front  into  a  canal ; 
surface  marked  by  very  fine,  undulating,  closely  arranged  revolving  lines,  which  are 
stronger  immediately  below  the  suture ;  suture  plain,  linear.  Spiral  angle  about  25°  ; 
breadth,  .37  inch. 

The  only  specimen  in  our  collection  is  a  fragment  consisting  of  about  two  and  a  half 
volutions,  the  last  one  too  imperfect  to  admit  of  the  determination  of  the  form  of  the 
aperture.  Another  fragment,  fig.  9,  #,  &,  is  from  the  collection  of  Dr.  Evans,  now  in 
the  possession  of  Dr.  Shumard  in  St.  Louis.  The  aperture  in  this  one  is  nearly  entire, 
and,  where  partially  exfoliated,  shows  in  some  places  a  thickening  of  the  shell,  with 
impressions  of  crenulations,  as  if  the  growth  had  been  interrupted  at  intervals.  It  is 
with  much  doubt  that  this  shell  is  referred  to  the  genus  Fusus. 

Locality  and  Position.  —  Sage  Creek.     Upper  part  of  division  No.  4  of  Section. 


FROM   THE    CRETACEOUS    FORMATION    OF    NEBRASKA.  393 

ROSTELLARIA    FUSIFORMIS,     n.  Sp. 
PLATE  III.  FIG.  10,  a,  Z>. 

Shell  elongate,  fusiform ;  spire  elongated ;  volutions  (number  unknown)  moderately 
convex,  marked  by  numerous  regular  rounded  oblique  flexuous  folds,  which  terminate 
abruptly  above  in  small  indistinct  nodes,  giving  a  sub-coronate  aspect  to  the  upper  part 
of  the  volutions ;  surface  unknown ;  suture  distinct  and  separated  from  the  row  of 
nodes  below  it  by  a  shallow  depression  ;  aperture  elongate,  widest  near  the  middle,  and 
narrowing  anteriorly  into  a  prolonged  canal.  Spiral  angle  35° ;  breadth,  1.1  inch. 

Our  specimen  is  imperfect  at  both  extremities,  and  so  exfoliated  as  to  preserve  none 
of  the  surface  markings.  The  folds  on  the  last  volution  appear  to  grow  more  irregular 
and  obscure  towards  the  aperture.  The  outer  lip  is  imperfect,  and  the  adhesion  of 
stony  matter  to  the  columella  prevents  the  positive  determination  of  the  generic  char- 
acters ;  but  the  general  aspect  of  the  surface,  the  longitudinal  folds  of  the  volutions, 
with  the  absence,  as  far  as  seen,  of  the  characteristic  features  of  other  genera,  induces 
its  reference  to  the  genus  Rostellaria.  In  the  broken  upper  extremity  of  the  shell,  a 
few  faint  spiral  bands  are  visible,  which,  if  continued,  would  mark  the  columella ;  but 
owing  to  the  exfoliation  of  the  specimen,  they  are  not  preserved. 

Locality  and  Position.  —  Sage  Creek.  Upper  clay  or  upper  part  of  division  No.  4 
of  Section. 

DENTALIUM  GRACILIS,  n.  sp. 
PLATE  III.  FIG.  11,  a-c. 

Slender,  terete,  gradually  enlarging  from  the  apex ;  section  sub-oval,  nearly  circular ; 
surface  distinctly  marked  by  rounded,  threadlike  stria?,  which  are  irregular  in  size,  and 
increase  in  number  by  implantation  between  the  larger  ones,  from  the  apex  towards 
the  aperture,  having  about  twenty-five  near  the  apex  and  fifty-two  at  a  point  where 
the  diameter  is  twice  as  great,  and  increasing  in  the  same  ratio  as  far  as  observed ; 
crossed  obliquely  by  extremely  fine  equal  striae,  which  ascend  from  the  outer  to  the 
inner  side  of  the  curve.  Spiral  angle  3  to  3i°.  Longest  diameter  of  largest  frag- 
ment, .2  inch ;  aperture  of  the  same,  .14  inch ;  diameter  of  smallest  fragment,  near 
the  apex,  .08  inch. 

This  we  believe  is  the  first  species  of  this  genus  described  from  the  cretaceous  for- 
mation of  this  country. 

Locality  and  Position.  —  Sage  Creek.     Upper  part  of  division  No.  4  of  Section. 

VOL.    V.    NEW    SERIES.  53 


394  DESCRIPTIONS    OF    NEW    SPECIES    OF    FOSSILS, 

HELIX  LEIDYI,  n.  sp. 
PLATE  III.  FIG.  12,  a,  I. 

Shell  sub-globose,  wider  than  long ;  spire  elevated ;  volutions  four  or  five,  last  one 
large  and  ventricose ;  suture  distinct ;  surface  unknown ;  aperture  unknown ;  outer 
lip  reflected ;  umbilicus  small,  or  perhaps  closed.  Spiral  angle  about  105°.  Length, 
.95  inch;  breadth,  1.14  inches.  The  last  volution  .65  of  the  whole  length. 

Our  specimen  is  merely  an  internal  cast  with  a  few  fragments  of  the  shell  adhering, 
no  portions  of  which  retain  the  surface  markings ;  but  faint  impressions  of  coarse, 
regular  lines  of  growth  are  left  by  the  interior  of  the  shell  upon  the  cast.  The  aper- 
ture is  distorted ;  though  it  was  apparently  wider  than  long.  At  the  base  of  the  shell 
the  cast  shows  a  distinct  reflection  of  the  lip. 

Locality  and  Position.  —  Near  the  head  of  Bear  Creek,  Mauvaises  Terres,  turtle  and 
bone  bed.  Eocene  Tertiary. 

AMMONITES  COMPLEXUS,  n.  sp. 
PLATE  IV.    FIG.  1,  a-/. 

Discoid ;  umbilicus  deep,  outer  volution  covering  one  half  to  two  thirds  of  the  next 
one  within ;  volutions  five  or  more,  ventricose,  nearly  twice  as  wide  as  high ;  orna- 
mented on  the  ventral  edge  by  about  ten  or  twelve  transverse  nodes,  slightly  elevated, 
and  extending  outwards  in  bifurcating  annulations,  which  cross  the  back  of  the  shell, 
uniting  again  on  the  opposite  side  in  the  same  manner.  Between  these  annulations 
are  often  other  intermediate  ones,  which  are  equally  prominent  on  the  back  of  the 
shell,  and  die  out  on  the  ventral  edge. 

These  nodes,  although  existing  in  the  young  shell,  are  scarcely  prolonged  into  annu- 
lating  ridges,  and  the  back  of  the  shell  is  smooth,  or  marked  only  by  the  ordinary 
lines  of  growth. 

In  a  young  specimen  of  .64  inch  in  diameter,  aperture  .34  inch  high,  and 
.49  inch  wide,  septa  formed  of  three  symmetrical  lobes  on  each  side.  Dorsal  lobe 
as  deep  as  the  dorsal  saddle,  but  wider,  deeply  divided  at  its  extremity,  and  or- 
namented by  two  large  terminal  branches,  the  outer  sides  of  which  are  deeply 
sinuate,  a  large  lateral  oblique  branch  midway  between  the  apex  and  base  of  the 
lobe.  Dorsal  saddle  deeply  divided  at  the  extremity  into  two  unequal  parts ;  the 
upper  one  again  deeply  bifurcate,  divisions  digitate  at  the  extremities;  ventral  di- 
vision bifid  at  the  tip;  a  small  branch  on  each  side  opposite  the  extremity  of  the 


FROM  THE  CRETACEOUS  FORMATION  OF  NEBRASKA.  395 

auxiliary  lobe.  Superior  lateral  lobe  extremely  contracted  in  the  middle  by  the 
lateral  branches  of  the  saddle;  divided  towards  its  extremity  into  three  unequal 
branches,  the  terminal  one  trifid  at  its  extremity,  the  lateral  ones  scarcely  digitate ; 
two  smaller  lateral  branches  towards  the  base.  Lateral  saddle  in  form  like  the  dorsal 
saddle,  with  the  ventral  division  larger  and  bipartite,  corresponding  to  the  dorsal  di- 
vision of  the  other.  Inferior  lateral  lobe  shorter  than  the  superior ;  contracted  near  the 
middle,  divided  into  three  sub-equal  branches,  the  lateral  ones  irregularly  digitate, 
and  the  terminal  one  trifid.  Ventral  saddle  oblique,  divided  by  the  auxiliary  lobe 
into  two  branches,  which  are  again  bifurcate,  with  the  extremities  obtusely*  bifid. 
Ventral  lobe  much  smaller  and  shorter  than  the  inferior  lateral  lobe,  sub-equally  tri- 
partite, with  the  divisions  sub-digitate.  A  small  bilobed  saddle  on  the  ventral  side  of 
the  last  lobe. 

The  characters  here  given  are  derived  from  a  small  specimen,  (PI.  IV.  fig.  1,  #,)  and 
from  the  inner  volutions  of  an  older  one,  (fig.  1,  £>,  c,)  while  in  the  outer  volutions  of 
the  same  specimen  the  lobes  and  saddles  become  very  much  crowded  together,  and 
exceedingly  complicated  in  their  structure ;  the  division  in  the  dorsal  lobe  becomes 
much  deeper,  all  the  divisions  already  noticed  are  more  complex,  the  sinuosities  ex- 
tended in  depth,  the  simple  digitations  become  complex  ramifications,  with  each 
division  again  sinuous  on  the  edges,  illustrating  in  a  remarkable  manner  the  devel- 
opment of  this  complicated  structure  as  the  animal  increases  in  age  and  dimensions. 
In  the  young  specimen  figured,  the  septa  in  the  interior  volutions  present  the  sim- 
plicity of  those  of  Goniatites  ;  while  the  outer  septa  of  the  same  specimen  exhibit  the 
structure  described  and  figured. 

In  the  older  specimen,  (PI.  IV.  fig.  1,  &,)  the  outer  septa  furnish  the  extremely 
complex  structure  given  in  figs.  1,  e,  and  1,  /,  which  include  the  dorsal  lobe  and  a 
part  of  the  dorsal  saddle,  as  well  as  the  superior  lateral  lobe,  disconnected  from  the 
preceding  parts ;  this  being  as  far  as  the  imperfection  of  the  specimen  and  the  ex- 
treme complication  of  the  structure  would  allow  one  to  follow  its  divisions;  while 
the  inner  volutions  present  precisely  the  same  structure  as  the  outer  volution  of  the 
younger  specimen. 

This  species  resembles  in  general  form  and  proportions  the  A.  Mantellii  of  Sowerby, 
but  the  annulating  ridges  are  less  strong,  and  the  nodes  on  the  inner  edge  very  dis- 
tinct. There  is  a  greater  difference,  however,  between  the  two  species  in  the  form  and 
details  of  the  lobes  of  the  septa. 

Locality  and  Position.  —  Great  Bend  on  the  Missouri.  Lower  part  of  division  No.  4 
of  Section. 


396  DESCRIPTIONS    OF    NEW    SPECIES    OF    FOSSILS, 

AMMONITES  PERCARINATUS,  n.  sp. 
PLATE  IV.  FIG.  2,  a-c. 

Discoidal,  depressed ;  umbilicus  wide  and  shallow ;  volutions  about  four  or  five,  all 
visible  in  the  umbilicus,  scarcely  one  fourth  of  each  embraced  in  the  succeeding  one ; 
shell  thin ;  surface  marked  by  thirty-eight  to  forty-five  prominent  flexuous  sharp  ribs 
some  of  which  originate  in  the  umbilicus,  and  others  upon  the  latero-ventral  margin, 
and  all  extend  to  the  dorso-lateral  edge,  where  they  bend  abruptly  forward,  and  ter- 
minate before  reaching  the  dorsal  line,  which  is  marked  by  a  thin  sharp  carina  extend- 
ing to  the  aperture.  Ribs  thickened  and  sometimes  nodose  towards  the  periphery. 

Our  specimens  are  all  casts  of  the  interior  with  fragments  of  the  shell  adhering,  and 
the  condition  is  such  as  to  give  no  means  of  determining  the  character  of  the  septa. 
Among  American  species,  it  resembles  in  general  appearance  the  A.  dbyssinius  of 
Morton,  (Jour.  Acad.  Nat.  Sci.,  Vol.  VIII.  p.  209,  PI.  X.  fig.  4,)  from  which  it  may  be 
at  once  distinguished  by  its  wider  umbilicus  and  dorsal  carina.  The  same  remarks 
would  apply  to  a  comparison  of  this  species  with  the  A.  splendens  of  Sowerby,  in  its 
young  state,  as  given  by  D'Orbigny  (Terrains  Cretaces,  p.  222,  PI.  63,  fig.  3).  It 
differs  also  from  the  A.  helius,  D'Orbigny,  (loc.  cit.,p.  187,  PI.  57,  figs.  I  and  2,)  in  its 
much  wider  umbilicus  and  more  sharply  elevated  carina,  while  in  the  European  species 
the  annulations  all  reach  the  umbilicus.  In  the  proportions  of  the  umbilicus  it  resem- 
bles the  A.  heliacus  and  A.  angulicostatus,  D'Orbigny,  (loc.  cit.,  PI.  25  and  46,)  but 
differs  in  its  sharp  dorsal  carina,  as  well  as  in  other  characteristics.  In  external  char- 
acters this  species  bears  a  close  resemblance  to  A.  aalensis,  Zeit.  (A.  candicans), 
D'Orbigny,  (loc.  cit,  p.  238,  PI.  63,)  from  the  upper  Lias. 

Locality  and  Position.  —  Five  miles  below  the  mouth  of  Vermilion  Eiver  on  the 
Missouri ;  in  division  No.  2  of  Section. 

HAMITES  MORTONI,  n.  sp. 

* 

PLATE  IV.    FIG.  3,  a-c. 

Cylindrical,  curved,  increasing  very  gradually  in  diameter  towards  the  larger  ex- 
tremity ;  surface  crossed  obliquely  by  sharp  annulations,  which  are  less  strong  upon 
the  ventral  side,  and  sharper  and  stronger  upon  the  dorsal  side.  A  few  of  these 
annulations  are  nodose  on  the  back,  and  some  of  them  also  bifurcate  and  again  unite 
after  making  half  a  revolution.  Annulations  narrower  than  the  space  between  them. 
Dorsal  lobe  shorter  than  the  superior  lateral  lobe,  bifurcate  (the  two  sides  a  little 


FROM  THE  CRETACEOUS  FORMATION  OF  NEBRASKA.  397 

dissimilar  in  details) ;  extremities  digitate,  the  one  on  the  right  having  two,  and  that  on 
the  left  three  divisions ;  sides  irregularly  sinuous ;  dorsal  saddle  as  long  but  not  as  wide 
as  the  dorsal  lobe,  bipartite  at  the  extremity,  the  right  branch  digitate  and  the  left 
subdivided ;  superior  lateral  lobe  longer  and  more  diverging  than  the  dorsal  lobe  or 
the  dorsal  saddle,  deeply  divided  into  two  principal  branches,  each  of  which  is  again 
subdivided,  with  numerous  shallow,  irregular  sinuosities  along  the  margin.  Lateral 
saddle  very  much  contracted  near  the  middle,  shorter  than  the  dorsal  saddle,  deeply 
divided  into  two  branches,  which  are  digitate.  Inferior  lateral  lobe  as  long  as  the 
superior  lateral  lobe,  but  narrower,  deeply  divided  into  two  branches,  each  of-  which 
is  again  divided,  the  divisions  digitate.  Ventral  saddle  shorter  than  the  lateral  saddle, 
oblique,  divided  into  three  lobes  at  top  with  smaller  ones  below.  Ventral  lobe  little 
more  than  half  as  long  as  the  inferior  lateral  lobe ;  bifid  at  the  apex,  and  with  three 
or  four  small  divisions  on  each  side. 

This  species  resembles  in  its  external  characters  the  H.  torquatus  of  Morton, 
(Synopsis,  PI.  XX.  fig.  4,)  but  the  annulations  are  relatively  closer  together  and  less 
acute  than  those  described  by  Dr.  Morton,  and  differ  in  being  sometimes  distinctly 
nodose  and  bifurcating.  The  fragment  possessed  by  us  makes  a  shorter  curve  than  the 
figure  cited  above.  In  addition  to  these  differences,  we  may  observe  that  our  shell 
makes  a  broader  or  more  circular  curve  than  is  usual  in  the  species  of  Hamites,  and 
moreover  appears  not  to  curve  precisely  in  the  same  plane,  resembling  in  this  respect 
the  genus  Helioceras  of  D'Orbigny,  while  the  septa  correspond  with  those  of 
Hamites. 

Locality  and  Position.  —  Near  Ked  Cedar  Island,  thirty-five  miles  below  Fort  Pierre, 
in  division  No.  4  of  Section. 

ANCYLOCERAS  1  NICOLLETII,  n.  sp. 
PLATE  IV.  FIG.  4. 

The  fragment  in  our  collection  appears  to  be  a  part  of  the  outer  chamber,  including 
the  abrupt  curved  portion,  of  a  shell  of  this  genus. 

Section  oval  or  sub-circular,  shell  thin,  abruptly  curved  towards  the  aperture,  surface 
marked  by  distinct  annular  costse,  which  encircle  the  shell  in  a  very  oblique  direction, 
and  become  obsolete  on  the  ventral  side  of  the  curve,  and  very  irregular  in  size  and 
distance  from  each  other  upon  the  lateral  portions  of  the  shell,  often  bifurcating  once 
or  twice,  with  sometimes  small  nodes  at  the  bifurcation,  becoming  more  prominent 
and  equidistant  upon  the  dorsum. 


398  DESCRIPTIONS    OF    NEW    SPECIES    OF    FOSSILS, 

This  fossil  resembles  the  fragment  figured  by  Dr.  Morton  as  Ammonoceratites  Con- 
radii,  (Jour.  Acad.  Nat.  Sci.,  Vol.  VIII.  p.  212,  PI.  X.  fig.  1,)  but  differs  from  that  in 
curving  more  abruptly,  and  could  scarcely  have  formed  a  circle  if  continued.  It  differs 
also  in  the  bifurcation  of  the  costse. 

It  is  with  some  hesitation  that  we  refer  this  fragment  to  the  genus  Ancylocems,  but 
the  form  of  the  curvature  and  character  of  the  annulations  more  nearly  resemble  the 
species  of  this  genus  than  any  other  which  we  know. 

Locality  and  Position.  —  Great  Bend  of  the  Missouri.     Division  No.  4  of  Section. 

BACULITES  OVATUS  and  B.  COMPRESSUS  of  Say. 

These  two  species  of  Baculites  were  first  described  by  Say,  and  subsequently  recog- 
nized and  redescribed  by  Dr.  Morton,  who  quotes  Say's  descriptions,  in  his  Synopsis  of 
the  Cretaceous  Fossils  of  New  Jersey.  The  Baculites  ovatus  had  also  been  recognized 
by  the  last-named  author  as  occurring  in  the  cretaceous  formation  in  Alabama,  as  well 
as  in  New  Jersey  and  Delaware,  showing  a  wide  geographical  distribution.  The 
B.  compressus^  regarded  by  Dr.  Morton  as  a  closely  allied  or  perhaps  identical  species, 
has  been  recognized  only,  so  far  as  we  know,  in  the  cretaceous  formation  of  the  Upper 
Missouri,  from  whence  it  was  first  described  by  Mr.  Say. 

Dr.  D.  D.  Owen,  in  his  report  on  Wisconsin,  Iowa,  and  Minnesota,  has  figured  (PI. 
VII.  fig.  6)  a  specimen  which  he  refers  with  doubt  to  B.  compressus  of  Say.  The 
specimen  in  question  is  from  Sage  Creek,  Nebraska,  and  is  a  fragment  apparently  of 
the  outer  chamber  with  the  shell  preserved ;  and  as  no  septa  are  shown,  it  is  impossible 
to  determine  satisfactorily  its  relations.  On  the  same  plate,  fig.  7,  another  fragment  is 
given,  also  without  septa,  and,  owing  to  the  bad  state  of  preservation,  it  shows  no  char- 
acters by  which  it  can  be  identified  with  any  known  species. 

The  -descriptions  and  figures  above  cited  comprise  the  amount  of  our  present 
knowledge  of  these  two  species  of  Baculites. 

In  our  collections  from  Sage  Creek,  and  from  various  localities  along  the  Missouri 
River,  we  have  a  considerable  number  of  well-preserved  specimens  of  Baculites,  which 
by  their  external  characters  are  readily  referred  to  two  distinct  species,  one  presenting 
in  its  section  a  regular  ovate  form,  or  sometimes  a  little  flattened  on  the  more  obtuse 
or  ventral  side,  the  other  presenting  a  section  of  very  depressed  ovate  form.  These 
two  forms  are  found  to  be  characterized  by  internal  differences,  which  are  constant  in 
all  the  specimens  examined. 

We  are  inclined  to  recognize  these  as  the   B.  ovatus  and  B.  compressus  of  Say, 


FROM  THE  CRETACEOUS  FORMATION  OF  NEBRASKA.  399 

although  there  are  in  the  details  of  internal  structure  slight  differences  between  the 
ovate  forms  from  the  Upper  Missouri  and  authentic  specimens  of  B.  ovatus  from  New 
Jersey. 

Inasmuch  as  the  figures  and  descriptions  heretofore  published  do  not  fully  charac- 
terize the  species,  or  enable  the  student  to  distinguish  these  from  allied  forms,  we  have 
endeavored  in  a  manner  to  supply  this  deficiency. 

BACULITES  OVATUS. 
PLATE  V.  FIG.  1,  a-c.     PLATE  VI.  FIGS.  1-7. 

B.  ovatus,  SAY,  Jour.  Acad.  Nat.  Sci.  Phil.,  Vol.  VI.  PL  V.  figs.  5,  6. 
«       "         "    Amer.  Jour.  Sci.,  Vol.  XVHI.  PI.  I.  figs.  6,  7,  8. 
"       "      MOBTOK,  Synopsis,  1834,  p.  42,  PI.  I.  figs.  6,  7,  8. 

Shell  elongated,  section  ovate,  sometimes  a  little  flattened  along  the  ventral  side ; 
dorsum  marked  only  by  lines  of  growth,  which,  passing  around,  continue  obliquely 
downward  for  about  two  thirds  of  the  distance  across  the  side,  where  they  curve  gently 
upwards  and  pass  over  the  ventrum  in  a  broad  arch,  thus  marking  the  outline  of  the 
aperture.  The  ventral  half  of  the  shell  is  marked  by  somewhat  regular,  transverse 
undulations,  which  follow  a  curve  parallel  to  the  lines  of  growth,  dying  out  entirely 
or  passing  into  the  lines  of  growth  on  the  dorsal  half  of  the  shell,  but  are  sometimes 
more  or  less  continued  upon  the  ventrum.  Aperture  (as  inferred  from  lines  of  growth) 
having  a  linguiform  extension  in  front  on  the  dorsum,  deeply  sinuated  at  each  side  on 
the  ventral  half,  and  broadly  arched  upwards  on  the  ventrum. 

Septa  symmetrical,  lobes  in  pairs  (excepting  the  ventral  lobe),  of  moderate  depth ; 
dorsal  lobe  wider  than  high,  very  little  shorter  than  the  lateral  superior  lobe,  divided 
into  two  widely  separated  branches,  each  of  which  is  tripartite,  and  the  divisions  sub- 
digitate.  Dorsal  saddle  as  long  as,  and  somewhat  wider  than,  the  superior  lateral  lobe ; 
deeply  divided  at  the  top  into  two  nearly  equal  parts  by  the  accessory  lobe,  each  part 
is  again  subdivided  into  three  or  four  branches  with  sinuate  margins.  Superior  lateral 
lobe  as  long  as,  but  narrower  than,  the  dorsal  saddle,  deeply  divided  at  the  extremity 
into  two  parts,  and  again  laterally  divided,  so  that  each  side  presents  two  principal 
branches,  the  terminal  ones  of  which  are  bifid  at  the  extremities ;  all  with  margins 
sinuate  and  sub-digitate.  Lateral  saddle  same  in  form  as  the  dorsal  saddle,  and  the 
details  of  the  ventral  side  of  the  one  agree  with  those  of  the  dorsal  side  of  the  other 
respectively.  Inferior  lateral  lobe  wider  than  the  superior  lateral  lobe ;  similar  in  its 
divisions,  except  that  it  is  more  deeply  divided  at  its  extremity  in  the  centre,  and  the 


400  DESCRIPTIONS    OF    NEW    SPECIES    OF    FOSSILS, 

terminal  divisions  are  less  distinctly  bifid ;  margins  and  extremities  sinuate  and  digi- 
tate. Ventral  saddle  as  wide  as  the  inferior  lateral  lobe,  two  thirds  as  high  as  the 
lateral  saddle,  and  less  deeply  divided  at  the  top  into  two  unequal  parts,  the  right  or 
dorsal  division  being  again  divided  into  two  unequal  parts,  the  lower  division  of  which 
is  somewhat  bipartite.  Ventral  lobe  narrow,  about  half  as  long  as  the  ventral  saddle, 
digitate  at  the  extremity,  and  deeply  sinuate  on  the  sides.  Angle  of  the  apex,  as 
deduced  from  the  convergence  of  the  dorsal  and  ventral  margins  by  the  measurement 
of  several  specimens,  3i  to  4°.  Longest  diameter  of  largest  specimens,  2.8  inches ; 
shortest  diameter  of  same,  1.7  inches.  Shell  on  the  ventrum,  .13  inch  thick;  on  the 
dorsum,  .1  inch ;  and  on  the  sides,  about  .05  inch  thick. 

In  a  septate  portion  of  a  specimen,  the  cast  gave,  in  its  largest  diameter,  1.4  inch  ; 
shortest  diameter,  .9  inch;  diameter  of  siphuncle,  .1  inch. 

Probable  length  of  largest  specimen  in  this  collection,  in  its  perfect  state,  3^  feet. 

Locality  and  Position.  —  Great  Bend  of  the  Missouri,  and  various  other  localities 
on  that  river  between  Fort  Pierre  and  the  mouth  of  Big  Sioux  River.  Fourth  division, 
ranging  through  its  entire  thickness. 

X 

BACULITES  COMPRESSUS. 
PLATE  V.  FIG.  2,  a,  I.  PLATE  VI.  FIGS.  8,  9. 

B.  compressus,  SAY,  Amer.  Jour.  Sci.,  Vol.  II.  p.  41. 
"  "          MOBTON,  Synopsis,  1834,  p.  43,  PI.  IX.  fig.  1. 

"  "  "        Jour.  Acad.  Nat.  Sci.  Phil.,  Vol.  VIII.  p.  211,  1842. 

Shell  elongate,  extremely  compressed,  gradually  tapering  from  the  base ;  section  very 
compressed  ovate ;  surface  marked  by  lines  of  growth,  which  cross  the  dorsum,  and, 
bending  obliquely  downwards,  curve  outwards  till  they  pass  the  centre  of  the  side; 
when  they  turn  more  abruptly  outwards  and  again  curve  upwards,  and  cross  the  ven- 
trum in  a  narrow  arch.  Lines  of  growth  more  prominent  on  the  dorsum,  forming 
faint  undulations  across  the  surface.  Septa  symmetrical ;  dorsal  lobe  very  wide,  and 
little  more  than  half  as  long  as  the  dorsal  saddle,  deeply  divided  into  two  widely 
separated  branches,  each  of  which  is  again  divided  into  two  unequal  parts,  which  are 
sharply  and  unequally  digitate.  Dorsal  saddle  twice  as  wide  as  the  superior  lateral 
lobe,  deeply  divided  by  the  acute,  sharply  digitate  auxiliary  lobe  into  two  nearly  equal 
parts,  each  of  which  is  subdivided  into  three  branches,  the  left  or  ventral  division 
larger  and  more  irregular  than  the  other ;  extremities  of  the  branches  obtuse.  Supe- 
rior lateral  lobe  narrow,  one  third  longer  than  the  dorsal  lobe,  divided  into  three 


FROM  THE  CRETACEOUS  FORMATION  OF  NEBRASKA.  40 1 

branches,  the  terminal  one  much  the  largest  and  deeply  bifurcate,  with  the  divisions 
smaller  than  the  lateral  branches ;  terminations  sharply  digitate.  Lateral  saddle 
slightly  wider  and  higher  than  the  dorsal  saddle,  auxiliary  lobe  longer  and  dividing  it 
into  two  parts  corresponding  in  their  details  to  those  of  the  dorsal  saddle.  Inferior 
lateral  lobe  shorter  than  the  superior  lateral  lobe,  and  deeply  divided  into  two  unequal 
branches,  that  on  the  ventral  side  being  unequally  divided  into  three,  and  that  on  the 
dorsal  side  into  two  parts,  all  sharply  digitate.  Ventral  saddle  one  third  smaller  than 
the  lateral  saddle,  deeply  and  somewhat  obliquely  divided,  by  a  sharply  digitate,  auxil- 
iary lobe,  into  two  nearly  equal  parts,  each  again  less  deeply  subdivided  and  having 
the  terminations  all  obtuse.  Ventral  lobe  narrow,  and  of  the  same  length  as  the 
auxiliary  lobe  of  the  dorsal  saddle,  sharply  digitate,  the  divisions  divaricate. 

Angle  of  the  apex  (as  deduced  from  measurements  of  imperfect  specimens)  about  three 
degrees.  The  longest  diameter  of  the  largest  fragment  (a  septate  cast)  in  our  collec- 
tion is  2.16  inches,  and  the  shortest  diameter  1.07  inches;  siphuncle  of  the  same  indi- 
vidual, .1  inch. 

In  addition  to  the  external  differences  already  mentioned,  we  may  state  that  the 
B.  compressus  is  never,  in  our  specimens,  marked  by  the  strong  undulations  which 
characterize  the  ventral  half  of  the  side  of  B.  ovatus.  The  internal  differences  are 
equally  striking  and  characteristic.  The  dorsal  lobe  of  B.  compressus  is  proportionally 
much  wider  and  less  deep,  and  the  two  branches  much  more  distant  and  more  divergent 
than  in  B.  ovatus.  The  central  or  siphuncular  portion  of  the  dorsal  lobe  in  B.  compres- 
sus presents  three  small  auxiliary  lobes,  the  two  outer  of  which  are  divergent  and 
digitate  at  their  extremities,  while  outside  of  these,  and  between  them  and  the 
main  branches  of  the  dorsal  lobe,  are  one  or  two  subordinate  digitations ;  while  in 
B.  ovatus  the  same  region  is  marked  by  only  two  short  and  parallel  extensions  with  a 
minute  point  between  them,  or  over  the  siphuncle,  and  some  undulations  on  each  side. 

In  B.  compressus  the  lobes  and  auxiliary  lobes  are  all  more  narrow,  longer,  and, 
together  with  all  their  subdivisions,  much  more  acute,  than  those  of  B.  ovatus.  The 
superior  lateral  lobe  in  the  two  species  likewise  presents  a  striking  difference.  In 
B.  compressus  it  is  divided  into  three  nearly  equal  brandies,  the  terminal  one  of  which 
is  again  deeply  bifurcate;  while  in  B.  ovatus  this  lobe,  in  consequence  of  the  greater 
depth  of  the  terminal  sinus,  is  divided  into  four  nearly  equal  branches,  the  two  ter- 
minal ones  being  bifurcated  by  a  small  sinus.  Similar  differences  are  noticed  in  the 
inferior  lateral  lobes  of  the  two  species.  Another  difference  may  be  observed  in  the 
relative  size  of  the  siphuncles,  that  of  B.  ovatus  being  proportionally  longer. 

VOL.   V.  NEW    SERIES.  54 


402  DESCRIPTIONS    OF    NEW    SPECIES    OF    FOSSILS, 

Locality  and  Position.  —  Sage  Creek  and  Great  Bend  of  Missouri  River,  etc.  Fourth 
division  of  Section. 

BACULITES  GRANDIS,  n.  sp. 
PLATE  VII.  FIG.  1,  2.     PLATE  VIII.  FIG.  1,  2.    PLATE  VI.  FIG.  10. 

Shell  elongate ;  section  varying  from  ovate  to  sub-cordiform ;  surface  of  cast  marked 
by  very  broad  and  strongly  elevated  undulations,  which  commence  at  the  dorsum  and 
pass  obliquely  downwards,  increasing  rapidly  in  size,  and,  crossing  the  side  of  the  shell 
in  a  broad  curve,  terminate  abruptly  on  the  ventro-lateral  region.  Undulations  less 
distinct  towards  the  smaller  extremity,  and  finally  become  obsolete.  Septa  very  deeply 
lobed,  principal  divisions  scarcely  divergent.  Dorsal  lobe  three  fourths  as  long  and 
twice  as  wide  as  the  superior  lateral  lobe ;  terminated  on  each  side  by  a  narrow  elon- 
gated branch,  which  is  irregularly  sinuate  and  digitate  at  the  extremity.  Dorsal  saddle 
shorter  and  wider  than  the  superior  lateral  lobe,  formed  of  four  branches,  the  two 
terminal  ones  much  the  larger,  and  each  of  them  bifid  at  the  extremity  by  a  small 
sinus  ;  the  whole  outline  more  or  less  sinuous  and  the  extremities  digitate.  Superior 
lateral  lobe  longer  by  one  fifth  than  the  inferior  lateral  lobe,  narrower  than  the  ventral 
saddle,  divided  at  its  extremity  by  a  deep  sinus  into  two  equal  parts,  which  are  simply 
digitate ;  above  these  are  two  unequal  branches  on  each  side ;  terminal  sinus  much 
deeper  than  the  lateral  ones.  Ventral  saddle  longer  and  about  as  wide  as  the  dorsal 
saddle,  more  deeply  divided  at  its  extremity  by  the  auxiliary  lobe  into  two  nearly  equal 
branches,  each  of  which  is  bifid  and  the  extremities  digitate,  ventral  side  with  three, 
and  dorsal  side  with  two  auxiliary  branches.  Inferior  lateral  lobe  shorter  and  broader 
than  the  superior  lateral  lobe,  divided  at  its  extremity  into  two  nearly  equal  branches, 
the  one  on  the  dorsal  side  bifid  at  the  tip  and  the  other  digitate,  with  an  auxiliary 
branch  on  the  ventral  side.  Ventral  lobe  as  long  as  the  auxiliary  lobe  of  the  ventral 
saddle,  but  wider  at  the  base,  digitate  at  its  extremity. 

Angle  of  the  apex  about  five  degrees.  Length,  as  deduced  from  the  measurement  of 
fragments,  by  the  convergence  of  the  dorsal  and  ventral  sides,  five  and  a  half  feet  or 
more.  Longest  diameter  of  a  fragment  not  distorted  by  pressure,  3.7  inches ;  shorter 
diameter  from  the  surface  of  undulations,  3.3  inches ;  in  the  depressions  between  the 
undulations,  2.95  inches. 

This  species  is  nearly  related  to  B.  ovatus  of  Say,  from  which  it  differs  in  its  much 
greater  size,  larger  apicial  angle,  much  stronger  and  more  extended  undulations,  which 
cross  the  entire  lateral  surface  of  the  shell.  The  section  is  more  obtusely  ovate ;  the 


FROM  THE  CRETACEOUS  FORMATION  OF  NEBRASKA.  403 

lobes  of  the  septa  are  much  deeper,  narrower,  and  less  divergent  in  their  branches ; 
the  digitations  are  sharper  and  more  directly  pointed  in  the  longitudinal  direction  of 
the  shell.  The  auxiliary  lobe  of  the  ventral  saddle  is  longer  in  this  species,  while  the 
extremities  of  the  terminal  branches  are  less  deeply  bifid  than  in  B.  ovatus.  In  this 
species  the  two  terminal  branches  of  the  superior  lateral  lobe  are  simply  digitate,  while 
in  B.  ovatus  they  are  deeply  bifid,  with  obtuse  sinuosities.  Externally  in  its  undula- 
tions on  the  sides,  this  species  resembles  B.  anceps  of  Lamarck,  but  will  be  readily 
distinguished  by  the  absence  of  a  dorsal  carina,  and  by  its  much  deeper  lobes  with  less 
divergent  divisions.  A  comparison  of  the  details  of  the  divisions  of  the  lobes  and 
saddles  shows  a  constant  difference  in  the  two  species. 

Locality  and  Position.  —  Mauvaises  Terres,  head  of  Bear  Creek.  Fifth  or  upper 
division  of  the  section,  and  but  a  few  feet  below  the  base  of  the  Titanotherium  bed  of 
the  Tertiary  formation.  From  this  point  it  is  known  to  extend  downwards  some 
twenty  or  thirty  feet,  and  probably  ranges  through  all  the  beds  of  the  fifth  division. 

The  occurrence  of  this  fossil  at  this  locality  indicates  very  distinctly  the  line  of 
demarcation  between  the  Cretaceous  and  Tertiary  formations  of  this  region ;  and  from 
the  absence  of  other  fossils  in  this  division,  as  far  as  known,  no  well-defined  line  has 
heretofore  been  drawn  between  the  deposits  of  the  two  periods ;  and  no  connection 
has  hitherto  been  shown  between  the  Eocene  formation,  containing  Mammalian  re- 
mains, with  the  Cretaceous  formation  below. 

In  examining  this  collection  of  specimens,  we  found  no  difficulty  at  the  outset  in 
distinguishing  the  Baculites  ovatus  and  B.  compressus  in  many  large  and  medium 
sized  shells.  At  the  same  time,  numerous  smaller  specimens  presented  a  structure  so 
different,  that  we  were  inclined  to  refer  them  to  distinct  species,  until  a  further  exami- 
nation of  specimens  still  more  minute  satisfied  us  that  they  were  all  to  be  referred  to 
the  one  species  of  B.  ovatus,  showing  different  degrees  of  development  dependent  upon 
age  and  growth.  A  careful  examination  under  a  magnifier  of  a  specimen  only  one 
twentieth  of  an  inch  in  diameter,  showed  the  septa,  which  are  so  complicated  in  the 
mature  specimen,  to  be  extremely  simple,  the  lobes  and  saddles  represented  by  simple 
undulations.  The  two  extremities  of  the  same  specimen  also  showed  different  degrees 
of  development,  as  seen  in  Plate  VI.  fig.  1,  a,  and  1,6,  which  are  from  the  smaller  and 
larger  extremities  respectively  of  the  specimen,  fig.  1.  An  individual  of  larger  growth 
(about  .1  inch  diameter)  shows  a  still  further  advance  in  the  development  of  the 
lobes  and  saddles,  with  their  principal  divisions,  as  shown  in  fig.  2,  2,  a.  A  still  fur- 
ther advance  is  shown  in  another  individual  of  .16  inch  diameter,  in  fig.  3,  3, «,  while 


404  DESCRIPTIONS    OF    NEW    SPECIES    OF    FOSSILS, 

fig.  4,  4,  a,  5,  5,  #,  show  an  increasing  degree  of  this  development  as  the  size  of  the 
individual  increases.  In  fig.  6  we  have  the  parts  fully  developed,  as  shown  in  the 
specimen,  Plate  V.  fig.  1,  «,  and  1,  6,  which  is  1.7  inches  in  its  shortest  diameter.  In 
all  the  smaller  specimens  the  section  is  more  broadly  ovate,  and  in  the  minute  ones 
nearly  circular,  while  the  angle  of  the  apex  is  nearly  double  that  which  we  have 
deduced  from  the  measurement  of  parts  of  the  adult  specimens. 

We  subsequently  ascertained  that  a  similar  progression  in  the  development  of  the 
septa  occurs  in  Ammonites  and  Scaphites  from  Nebraska;  and  in  even  a  more  remark- 
able degree  than  in  the  Baculites.* 

These  facts  in  relation  to  Ammonites  we  have  shown  in  the  A.  complexus,  which  is 
represented  in  two  stages  of  development ;  while  the  septa  of  the  inner  volutions  of 
the  small  individual  figured  are  no  more  undulated  than  some  of  the  older  and  more 
simple  forms  of  Goniatites,  leading  unavoidably  to  the  conclusion  that  the  animal,  in 
its  embryonic  and  extremely  young  state,  is  provided  only  with  simple  septa,  like  the 
more  ancient  and  recent  Nautili. 

The  Scaphites  nodosus  of  Owen,  which,  in  its  adult  state,  has  extremely  complicated 
septa,  has  been  proved,  by  a  careful  examination,  to  present  in  its  successive  stages  of 
growth  the  same  development  as  occurs  in  Baculites  and  Ammonites,  showing  that 
this  law  of  development  is  common  to  these  three  genera ;  from  which  we  may  infer 
that  it  may  pervade  the  entire  family  of  Ammonitidae. 

These  facts  have  an  important  bearing  upon  the  study  of  this  family  of  fossils,  and 
show  in  a  remarkable  degree  how  beautifully  the  progression  from  lower  to  higher 
forms  of  animal  organization,  as  exhibited  in  the  introduction  of  successive  creations 
upon  the  same  general  plan  from  the  older  to  the  more  recent  geological  epochs,  is 
here  simulated  and  illustrated  by  the  phases  of  development  in  a  single  individual 
in  its  progress  from  the  young  state  to  maturity. 

*  We  are  aware  that  the  same  characteristics  have  been  shown  in  some  European  species  of  Am- 
monites ;  but  these  observations  were  made  independently  of  any  hints  from  other  sources ;  and  we  are  not 
able  to  ascertain  from  any  publication  within  reach,  that  such  features  have  been  discovered  in  Baculites  or 
Scaphites. 


FROM  THE  CRETACEOUS  FORMATION  OF  NEBRASKA. 


405 


Section  of  the  Members  of  the  Cretaceous  Formation  as  observed  on  the  Missouri  River, 
and  thence   Westward  to  the  Mauvaises  Terres. 


•3 

£ 
u 


Clays,  sandstones,  etc.,  etc.,  containing  remains  of  Mammalia.     The  "entire 
thickness  of  this  formation  in  the  Bad  Lands  is  from  25  to  250  feet. 

5.  -j       Arenaceous  clay  passing  into  argillo-calcareous  sandstone.     80  feet. 

f  Plastic  clay  with  calcareous  concretions  containing  numerous  fossils.     250 

J  to  350  feet. 

'   I  This  is  the  principal  fossiliferous  bed  of  the  cretaceous  formation  upon 

[  the  Upper  Missouri. 

(  Calcareous  marl,  containing  Ostrea  congesta,  scales  of  fishes,  etc.     100  to 

'    (  150  feet. 

2.  •]       Clay  containing  few  fossils.     80  feet. 

1,  -j       Sandstone  and  clay.     90  feet. 

Buff-colored  magnesian  limestone  of  the  carboniferous  period. 


List  of  Fossils  heretofore   identified  and  described  from   the    Cretaceous  Formation  of 

Nebraska. 


Nautilus  Dekayii,  Morton. 
Ammonites  placenta,  Dekay. 

"          mandanensis,  Morton. 
"          Nicolletii,  " 

"          Conradii,  " 

"          abyssinius, 
"          cheyennensis,  Owen. 
"          Nebrascensis,      " 

lenticularis, 

"          opalus,  " 

moreauensis,        " 
Scaphites  nodosus, 

"         comprimus, 
Baculites  ovatus,  Say. 

compressus,  Say. 
Belemnites  Americanus,  Morton. 

Rostellaria  Nebrascensis,  Evans  and  Shumard. 


Solarium  flexistriatum,  Evans  and  Shumard. 
Pholadomya  elegantula,      " 
Mytilus  galpinianus,  " 

Avicula  linguae formis, 

"       triangularis,  " 

"       cretacea,  Conrad. 
Ostrea  congesta, 

"     vesicularis,  Lamarck  (on  the  authority  of  M. 

Nicollet's  list). 
Inoceramus  Barabini,  Morton. 

(=  I.  Crispii  ?  Mantell.) 
"  sagensis,  Owen. 

"          Nebrascensis,  Owen. 
Cytherea  Missouriana,  Morton. 
Tellina  occidentalis, 
Cucullea  Nebrascensis,  Owen. 
Anomia  tellinoides,  Morton. 
Hypponix  borealis,       " 


406  DESCRIPTIONS    OF    NEW    SPECIES    OF    FOSSILS, 


List  of  Species  common  to  the  Cretaceous  Formations  of  Nebraska  and  New  Jersey. 

Nautilus  Dekayii,  Belemnites  Americanus, 

Ammonites  placenta,  Inoceramus  Barabini, 

"  Conradii,  at  Prairie  Bluff,  Alabama,  Ostrea  larva. 

Baculites  ovatus, 

List  of  New  Species  of  Fossils  described  in  the  Preceding  Paper. 

Lingula  subspatulata,  Natica  obliquata, 

Caprinella  coraloidea,  "       paludinseformis, 

Capulus  occidentalis,  Actseon  concinnus, 

Avicula  Haydeni,  Buccinum  vinculum, 

Pecten  rigida,  Fusus  Shumardi, 

Lucina  subundata,  "      constrictus, 

Cytherea  orbiculata,  "  ?  tenuilineata, 

"        tenuis,  Rostellaria  fusiformis, 
Crassatella  Evansi, 

Pectunculus  Siouxensis,  Dentalium  gracilis, 
Nucula  subnasuta, 

"       ventricosa,  Helix  Leidyi, 

Inoceramus  Conradi,  Hamites  Mortoni, 

"           tenuilineatus,  Ammonites  complexus, 

"           convexus,  percarinatus, 

"           sublsevis,  Ancyloceras  Nicolleti, 

"           fragilis,  Baculites  grandis, 

Natica  concinna,  Callianassa  Danai. 

Among  all  the  collections  made  in  Texas  by  Dr.  Roemer  and  others,  and  of  all 
those  brought  by  the  Boundary  Survey  Expedition,  and  other  surveying  and  exploring 
parties,  which  we  have  seen,  there  is  but  a  single  species  which  we  regard  ds 
doubtfully  identical  with  one  from  Nebraska.  This  is  the  Inoceramus  Barabini  of 
Morton  (==  I.  Crispii,  Mantell  [?]). 

The  most  striking  distinction  between  the  fossils  of  the  cretaceous  formation  of 
Nebraska,  and  that  of  New  Jersey  and  other  parts  of  the  United  States,  is  the  almost 
total  absence  of  Ostrea,  only  two  small  species  being  known  in  the  Missouri  region, 
while  Exogyra  is  quite  unknown. 

The  same  region  has  not  hitherto  furnished  a  single  Echinoderm  in  all  the  collec- 
tions that  have  been  made  there  during  half  a  century. 


FROM  THE  CRETACEOUS  FORMATION  OF  NEBRASKA.  407 


Explanation  of  Plates. 

PLATE  I. 

FIG.  1,  a.  Fragment  of  Callianassa  Danai,  natural  size. 
"     1,  b.  The  same,  enlarged. 

FIG.  2,  a.  Lingula  subspatulata. 
"     2,  I.  A  portion  of  the  surface,  enlarged. 

FIG.  3,  a.  Caprinella  coraloidea,  the  external  shell  partially  removed ;  showing  the  interior  septate  portion, 

with  the  thick  fibrous  shell  attached  on  the  inner  side  of  the  curve. 

"     3,  I.  Exterior  view  of  the  inner  septate  portion  denuded  of  the  shell,  and  showing  a  shallow  longi- 
tudinal groove  from  the  base  to  near  the  apex. 
"     3,  c.  Lateral  view  of  the  septate  interior  portion  of  the  shell. 
"     3,  d.  Transverse  section  of  the  shell  at  the  larger  extremity. 

3,  e.  A  portion  of  the  fibrous  or  tubular  part  of  the  shell,  enlarged,  showing  solid  prismatic  columns, 

which  are  marked  by  parallel  divisional  planes  transverse  to  the  longitudinal  axis. 
3,/.  A  single  column  still  further  enlarged,  showing  stria?  parallel  to  the  divisional  planes. 

FIG.  4,  a.     Pecten  rigida,  natural  size. 
"     4,  Z>,  c.  The  left  and  right  valves,  four  times  magnified. 

FIG.  5,  a.  Avicula  Haydeni,  natural  size. 
"     5,  b.  The  same,  four  times  enlarged. 

FIG.  6,  a.  Lucina  subundata,  natural  size. 
"     6,  b.  A  portion  of  the  surface,  magnified. 

FIG.  7.   Cytherea  orbiculata,  natural  size. 

FIG.  8,  a.  Cytherea  tennis^  natural  size. 
"     8,  b.  Same,  four  times  magnified. 
"     8,  c.  A  portion  of  the  surface,  still  further  magnified. 

FIG.  9,  a-  Crassatella  Evansi,  exterior  or  left  valve. 
"     9,  b.  Interior  of  same. 
"     9,  c.  Surface-markings,  enlarged. 
"     9,  d.  A  cast  of  same  species. 
"     9,  e.  Profile  view  of  cast. 

FIG.  10,  a,  b.  Nucula  subnasuta. 
"     10,  c.  Surface-markings,  magnified. 

FIG.  11,  a.  Nucula  ventricosa,  natural  size. 
"     11,  b.  The  same,  greatly  magnified. 

"    12.  Pectunculus  Siouxensis,  a  cast  of  the  left  valve. 


408  DESCRIPTIONS    OF   NEW    SPECIES    OF    FOSSILS, 

FIG.  13,  a.  Capulus  occidentalism  cast  of  interior  of  convex  valve. 

"  13,  b.  Profile  view  of  same. 

"  13,  c.  Base  of  same. 

"  13,  d.  Surface-markings  of  the  base,  magnified. 


PLATE  II. 

FIG.  1,  a.  Inoceramus  sublavis,  right  valve,  nearly  entire. 
"     1,  b.  A  portion  of  the  surface  magnified. 

FIG.  2,  a.  Inoceramus  convexus,  left  valve. 
"     2,  b.  Profile  of  same,  looking  upon  the  hinge  lirie. 

FIG.  3,  a.  Inoceramus  tenuilineatus,  left  valve. 
"     3, 1.  A  portion  of  the  surface  of  the  anterior  part  of  the  shell,  magnified. 

FIG.  4.  A  portion  of  the  striated  surface  of  the  shell  of  Inoceramus  sagensis,  magnified. 

FIG.  5,  a.  Inoceramus  Conradi,  the  exterior  portion  of  the  shell  of  both  valves,  which  are  distorted  by 

pressure. 
"     5,  b.  Surface  of  same,  magnified. 

FIG.  6,  a.  Inoceramus  fragilis,  natural  size. 
"     6,  b.     Surface  of  same,  magnified. 

PLATE  III. 

FIG.  1,  a,   b.  Natica  obliquata,  two  views  of  the  same  shell. 

FIG.  2,  a.  Natica  concinna,  natural  size. 
"     2,  J,  c.  Two  views  of  the  same,  magnified. 
"     2,  d.  The  surface  striae,  magnified. 

FIG.  3,  a,  b.  Natica  paludinceformis,  two  views  of  individuals  of  different  size. 
"     3,  c.  The  surface  magnified,  showing  the  cancellated  striae. 

* 
FIG.  4,  a.  Actaon  concinnus,  natural  size. 

"     4,  5,  c.  Same,  magnified  nine  times. 

"     4,  d.  Surface-markings,  highly  magnified. 

FIG.  5,  a.  Buccinum  vinculum,  natural  size. 
"     5,  b.  Magnified  view  of  the  same. 

FIG.  6,  a.  Fusus  Shumardi,  natural  size. 

"     6,  b.  Magnified  view  of  the  opposite  side  of  the  same  shell. 
"     6,  c.  Surface-markings,  magnified. 


FROM  THE  CRETACEOUS  FORMATION  OF  NEBRASKA.  409 

FIG.  7.  a,  Fusus  constrictus,  natural  size. 
"  7,  Z>,  c.  Magnified  views  of  the  same. 
"  7,  d.  Magnified  views  of  surface-markings. 

FIG.  8,  a,  b.  Fusus  ?  tenuilineatus,  two  views  of  a  fragment,  preserving  about  two  volutions  and  a  half. 

"     8,  c.  Surface-markings,  highly  magnified. 

FIG.  9,  a,  b.  Two  views  of  a  fragment  of  the  same,  showing  the  aperture.     From  the  collection  of  B.  F. 
Shumard. 

"     9,  c.  Surface  of  same,  magnified. 

FIG.  10,  a,  b.  Rostellaria  fusiformis,  two  views  of  the  same  individual. 

FIG.  11,  a.  Dentalium  gracilis,  fragments,  natural  size. 
"     11,  b.  Transverse  section  of  the  larger  extremity. 
"     11,  c.  Magnified  view  of  surface. 

FIG.  12,  a,  b.    Helix  Leidyi,  two  views   of  the   same   individual.      From   the   Eocene   Tertiary   of  the 
Mauvaises  Terres. 

PLATE  IV. 

FIG.  1,  a.  Ammonites  complexus,  a  young  individual. 

"  1,  b,  c.  Two  views  of  a  fragment  of  a  larger  shell. 

"  2,  d.  Form  of  the  septa,  as  shown  in  the  young  specimen. 

FIG.  1,  e.  Superior  lateral  lobe  of  the  adult  specimen. 

"  I,/.  Dorsal  lobe  of  the  same  individual. 

FIG.  2,  a,  J,  c.  Ammonites  peracutus,  views  of  different  individuals. 

FIG.  3,  a.  Hamites  Mortoni,  a  fragment. 
"     3,  b.  Section  of  larger  extremity. 
"     3,  c.  Arrangement  of  septa  in  the  same  specimen. 

FIG.  4.  Ancyloceras  Nicolletii,  a  fragment. 


PLATE  V. 

FIG.  1,  a.  Baculites  ovatus,  showing  the  form  of  aperture,  surface  stria?,  and  undulations  upon  the  ventral 

half  of  the  shell. 

"     1,  b.  A  fragment,  showing  septa. 
"     1,  c.  Transverse  section  of  the  same. 

FIG.  2,  a.  Baculites  compressus,  showing  the  form  of  the  aperture,  surface  striae,  and  arrangement  of  septa 

towards  the  base  of  the  figure. 
"     2,  b.  Transverse  section  of  the  same. 
VOL.    V.    NEW    SERIES.  55 


410  DESCRIPTIONS    OF    NEW    SPECIES    OF    FOSSILS, 


PLATE  VI. 

Illustrations  of  the  Septa  in  Baculites  Ovalus,  B.  Compressus^  and  B.  Grandis. 

FIG.  1.  Baculites  ovatus,  a  fragment  of  an  extremely  young  individual. 
"     1,  a.  Plan  of  a  septum  in  the  smaller  extremity  of  fig.  1. 
"     1,  b.  A  septum  at  the  larger  extremity  of  the  same. 

FIG.  2.  A  larger  individual  of  the  same  species. 
"     2,  a.  Plan  of  a  septum  in  fig.  2. 

FIGS.  3,  4,  and  5,  are  young  individuals  of  larger  growth  than  the  preceding,  and  of  which  figs.  3,  a,  4,  a, 
and  5,  a,  respectively  show  plans  of  the  septa. 

FIG.  6.  Plan  of  septum  in  an  adult  individual  of  Baculites  ovatus. 

FIG.  7.  Superior  lateral  lobe  of  Baculites  ovatus,  for  comparison  with  corresponding  parts  of  B.  compressus, 
fig.  9,  and  B.  grandis,  fig.  10. 

FIG.  8.  Plan  of  septum  in  a  full-grown  individual  of  Baculites  compressus. 
FIG.  9.  Superior  lateral  lobe  of  B.  compressus. 
FIG.  10.  Superior  lateral  lobe  of  B.  grandis. 

PLATE  VII. 

FIG.  1.  Baculites  grandis,  a  fragment  of  the  septate  portion  of  the  shell. 

FIG.  2.  Transverse  section  of  B.  grandis.  The  inner  figure  is  a  section  of  the  smaller  extremity  of  fig.  1. 
The  second  figure  is  of  the  smaller  extremity  of  PI.  VIII.,  fig.  1,  measured  in  the  depressions 
between  the  undulating  ridges ;  and  the  outer  figure  is  the  measurement  over  the  ridges  which 
give  a  different  outline  to  the  section. 

FIG.  3  and  4.  Tracks  of  Planarian  worms  ? 

PLATE  VIII. 

FIG.  1.  Baculites  grandis ;  fragment  of  the  outer  chamber,  showing  the  transverse  undulating  ridges  whjch 
characterize  this  species  externally. 

FIG.  2.  Plan  of  a  septum  of  B.  grandis. 


FROM  THE  CRETACEOUS  FORMATION  OF  NEBRASKA.  411 


ADDITIONS     AND     CORRECTIONS. 

SINCE  the  preceding  paper  was  communicated,  we  have  had  an  opportunity  of  examining  more  extensive 
collections  of  specimens  from  the  Nebraska  Territory,  brought  down  by  Dr.  Hayden.  Among  these  are 
better  preserved  specimens  of  several  species  here  described,  which  enable  us  to  determine  their  characters 
with  more  precision  than  could  be  done  with  our  former  collections. 

Page  391.  Ftrsus  CONSTRICTUS.  An  examination  of  a  larger  and  better  preserved  specimen  induces  us  to 
regard  this  fossil  as  belonging  to  the  genus  BUCCINUM. 

Page  393.  DENTALIUM  GRACILIS.     Seventh  line  of  description,  for  "  spiral  angle  "  read  "  apicial  angle." 
Page  394.  HELIX  LEIDYI.     The  aperture  is  ovate,  subangular  behind. 

Page  396.  HAMITES  MORTONI.  This  fossil  presents  some  characters  incompatible  with  the  genus  Hamites, 
and  may  be  placed  under  Ancyloceras,  if  we  adopt  the  characters  of  that  genus  as  given  by  Pictet.  In  the 
same  manner  the  Ancyloceras  ?  Nicolletii  will  be  included  under  the  genus  Ancyloceras  as  defined  by  Pictet, 
but  not  as  limited  by  D'Orbigny. 

Page  401.  Last  word  on  the  page,  for  "  longer"  read  " larger." 


NOTE. 

IN  the  spring  of  1853,  the  writer  of  this  note  was  induced  to  provide  the  means  for  a  collector  to  visit  and 
explore  some  portions  of  the  Mauvaises  Terres  of  Nebraska.  He  was  assured  that  no  government  expedition 
would  be  sent  there  that  year;  and  being  unable  to  learn  that  any  private  expedition  was  contemplated,  he 
concluded  that  the  field  would  be  unoccupied,  and  hoped  that  some  new  light  might  be  thrown  upon  these 
distant  regions,  which  had  but  just  begun  to  yield  their  treasures  to  the  geologist  and  palaeontologist.  One  of 
the  principal  objects  of  this  expedition  was  the  discovery  of  the  fossil  flora  of  this  period,  so  prolific  in 
remains  of  Mammalia,  as  well  as  to  determine  more  clearly  the  relations  between  the  Cretaceous  formations 
of  the  Missouri  Valley  and  those  of  the  region  especially  known  as  the  Mauvaises  Terres. 

Circumstances  which  it  is  not  neccessary  to  detail  here,  and  over  which  the  writer  or  the  exploring  party 
had  no  control,  frustrated  in  a  great  measure  the  original  objects  of  the  expedition. 

The  collections  made,  and  facts  ascertained,  during  the  short  period  which  the  party  remained  on  the 
ground,  have  contributed  something  to  our  knowledge  of  the  geology  of  this  region  ;  and  the  preceding  new 
species  from  the  Cretaceous  formation  of  the  Northwest  are  not  without  interest.  These  would  have  been 
given  to  the  public  at  an  earlier  period,  but  have  been  postponed  at  the  especial  request  of  other  parties 
having  new  species  from  the  same  region.  These  have  already  been  made  known,  and  are  cited  in  the  list 
of  published  species  given  on  page  405 ;  there  is,  therefore,  no  longer  any  reason  for  delaying  the  publi- 
cation of  the  foregoing  species,  which,  it  will  be  seen,  comprise  a  number  equal  to  all  that  have  before  been 
described  from  the  Cretaceous  formation  of  that  country. 

J.  H. 


XVIII. 

Supplement  to  Memoir  XL  of  this  Volume,  on  "  The  Numerical  Relation  between  the 
Atomic  Weights,  with  some  Thoughts  on  the  Classification  of  the  Chemical  Elements."" 

SINCE  the  printing  of  the  above  memoir,  the  author  has  altered  the  details  of  his  clas- 
sification so  far  as  regards  the  metallic  elements,  —  1st,  by  transferring  several  members 
of  the  Four  Series  to  the  Three  Series ;  2d,  by  subdividing  each  of  these  series  into 
groups.  The  classification  as  thus  altered  is  presented  in  the  table  accompanying  the 
memoir,  and  conforms  to  the  principle  of  chemical  series  more  closely  than  that  given 
in  the  table  originally  intended  to  accompany  the  memoir,  and  subsequently  published 
in  the  American  Journal  of  Science  and  Arts,  Second  Series,  Vol.  XVII.  p.  387. 
The  serial  relations  of  the  metallic  elements  may  be  traced,  in  the  first  place,  in  the 
groups  considered  each  as  a  whole,  and,  in  the  second  place,  in  the  members  of  any  one 
group  by  itself.  From  the  limited  amount  of  space  assigned  to  this  supplement,  it  will 
not  be  possible  to  follow  out  these  relations,  but  they  will  be  suggested  to  any  chemist 
on  inspecting  the  table.  Most  of  the  rarer  metals  have  been  omitted  in  it,  not  only 
because  their  properties  are  generally  very  imperfectly  known,  but  also  because  the 
table  was  chiefly  intended  for  teaching  elementary  chemistry. 

J.  P.  C. 

CAMBRIDGE,  April  5th,  1856. 


ERRATA. 

Page  239,  line  IS,  for  mutantis,       read  mutatis. 
"    241,    "    14,    "    Eight  Series,    "     Nine  Series. 
"    256,    "    15,    "    Rhombic,         "     Hexagonal. 


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